The subject matter disclosed herein relates generally to turbine systems, such as gas turbine systems, and more particularly to approaches for cooling a hot gas path component in such a turbine system.
Turbine systems are widely utilized in fields such as power generation. A conventional gas turbine system utilized for power generation includes a compressor, a combustor, and a turbine. Typically such a gas turbine system produces high temperature flows of gas through a flow path defined by the components of the turbine. Higher temperature flows generally are desired as such higher temperatures may be associated with increased performance, efficiency, and power output of the gas turbine system. That is, the high temperature flows are typically associated with or indicative of the types of combustion and flow conditions one looks for in a properly functioning gas turbine system.
However, as might be expected, such high temperatures can cause excessive heating of the components within the flow path. Such heating may in turn cause one or more of these components to fail. Thus, because of the desirability of these high temperature flow conditions in a properly running system, the components that are subjected to high temperature flows must be cooled to allow the gas turbine system to operate with flows at increased temperatures.
Various strategies may be employed for cooling components that are subjected to high temperature flows. These components are typically known as hot gas path components. However, many of the cooling strategies employed result in comparatively low heat transfer rates and non-uniform component temperature profiles, which may be insufficient to achieve the desired cooling.
In all of these exemplary gas turbine engine components, thin metal walls of high strength superalloy metals are typically used for enhanced durability while minimizing the need for cooling thereof. Various cooling circuits and features are tailored for these individual components in their corresponding environments in the engine. For example, a series of internal cooling passages, or serpentines, may be formed in a hot gas path component. A cooling fluid may be provided to the serpentines from a plenum, and the cooling fluid may flow through the passages, cooling the hot gas path component substrate and coatings. However, this cooling strategy typically results in comparatively low heat transfer rates and non-uniform component temperature profiles.
Micro-channel cooling has the potential to significantly reduce cooling requirements by placing the cooling as close as possible to the heat zone, thus reducing the temperature delta between the hot side and cold side for a give heat transfer rate. However, when applying the structural coating over micro-channels, the most critical regions are the top edges of the channels. If these edges are not sharp and at right angles, then flaws can be initiated at the interface between the substrate base metal and the structural coating, either as a gap, a crack starter, or as a small void that can propagate flaws into the coating as it is deposited.
It would therefore be desirable to provide a method for forming micro-channels in a component with channel edges formed as sharp right angles, without further processing of the substrate base metal.